The present invention relates to amorphous saturated hydrocarbon thermoplastic substrates having improved adhesion properties.
Amorphous saturated hydrocarbon thermoplastics, such as polyvinylcyclohexane, have found uses in a variety of applications including multilayered or laminated articles such as optical disc media. Such multilayered or laminated articles typically comprise a layer of hydrogenated aromatic polymer and an additional layer of a metal or a polymeric material. However, previous attempts at applying metals or polymers to such hydrogenated aromatic polymer surfaces have resulted in poor adhesion.
JP-4-335009 by Tanaka et al. discloses a hydrogenated hydroxyl-substituted styrene copolymer with increased adhesion to recording film layers. However, such copolymers are not commercially available and are typically obtained by an expensive multistep process.
JP-3-59833 by Kato et al. discloses a hydrogenated vinyl aromatic polymer optical disc substrate having improved adhesion by treating the substrate with a mixed solution of sulfuric acid and chromic acid, while JP-3-59832 by Kato et al. discloses a similar method using fuming nitric acid. However, these wet corrosive methods are hazardous and can lead to equipment degradation.
U.S. Pat. No. 5,073,427 by Suga et al. discloses an optical disc surface treated with a fluorine-containing gas to improve adhesion to a recording layer formed thereon. However, this method is impractical since fluorine is toxic and corrosive, and hydrofluoric acid is produced as a byproduct.
Therefore, a need remains for amorphous saturated hydrocarbon thermoplastic substrates having enhanced adhesion properties, wherein the enhanced adhesion is obtained by an efficient and effective method without using or producing wet corrosive materials which causes equipment degradation.